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Exhaust fracture
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Al.
Flying Brick Rider


Joined: 28 Oct 2005
Posts: 292
Location: West of Ireland

PostPosted: Sun Jun 11, 2017 6:24 pm    Post subject: Exhaust fracture Reply with quote

Funny noise developed today like muffler hole.
Think I found a crack in outer header pipe as it enters group.
Any up to date information - I read older posts.

Funny thing it was very noisy on the motorway at about 75 mph.
It got quiet again. Then on way home it got noisy on motorway for a short while.

Son in law is a magic welder - made his own system for a Fireblade!!!
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SugarHillCTD
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Joined: 10 Oct 2007
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Location: Sugar Hill, NH, USA

PostPosted: Sun Jun 11, 2017 7:16 pm    Post subject: Reply with quote

Is this a K1100 or K100, or did I miss where you stated this?

It sounds like your problem is with your 1100, correct?

(you might fill out the signature part so it shows up on your posts)
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Al.
Flying Brick Rider


Joined: 28 Oct 2005
Posts: 292
Location: West of Ireland

PostPosted: Mon Jun 12, 2017 4:22 am    Post subject: Reply with quote

Apologies.
1994 K1100 LTSE
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SugarHillCTD
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PostPosted: Mon Jun 12, 2017 5:47 am    Post subject: Reply with quote

As you may have read in older posts, the junction where the 4 headers merge into the silencer is a common site for failure. There have been various levels of success in repairing this type of fracture. Having a good welder in the family sounds like you should be good to go.

The change in sound might be due to expansion of the metal, possibly mitigated at times by ambient road/tyre/machine noise.

By the way, I had asked about 100 vs. 1100 because the 100 exhaust system has header pipes that just slip in and are not welded.
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'92 K100RS4V Pearl White
2009 R1200RT Black
gone-'14 Triumph Daytona 675R
IBA Several-SS1k, BBG, 50CC NYC to S.F.
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Al.
Flying Brick Rider


Joined: 28 Oct 2005
Posts: 292
Location: West of Ireland

PostPosted: Mon Jun 12, 2017 6:08 am    Post subject: Reply with quote

Thanks for all that and advice on signature!
I saw pictures in old posts with reinforcing plate over junction.
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Al.
Flying Brick Rider


Joined: 28 Oct 2005
Posts: 292
Location: West of Ireland

PostPosted: Thu Jun 15, 2017 4:59 pm    Post subject: Reply with quote

Pig of a job to get cover plate off
Back bolt inaccessible top or bottom.
Have to try smaller tools Twisted Evil
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Flying Duck
PsyKotic Waterfowl


Joined: 27 Jan 2005
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Location: Bumf***, WA

PostPosted: Thu Jun 15, 2017 6:15 pm    Post subject: Reply with quote

You don't need to remove the cover plate (a.k.a heat shield) to get the exhaust off.

Just the 8 flange nuts to the head, the big bolt at the rear that holds the can up and the one on the right.
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Al.
Flying Brick Rider


Joined: 28 Oct 2005
Posts: 292
Location: West of Ireland

PostPosted: Fri Jun 16, 2017 6:17 am    Post subject: Reply with quote

Well I was hoping to weld it on the bike!
People said it was better to do this as it might warp.

What about electrics if not gas.
May be mig/tig
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whyoldbill
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Joined: 12 Jun 2006
Posts: 440
Location: in the boonies, northwest of Columbus, Ohio

PostPosted: Fri Jun 16, 2017 3:59 pm    Post subject: Reply with quote

Al. wrote:
Well I was hoping to weld it on the bike!
People said it was better to do this as it might warp.

What about electrics if not gas.
May be mig/tig


Mine was cracked across the tops of the pipes at the collector, so it had to come off.
I fashioned up a jig made of plywood to hold the pipes in the correct position.
Mine was welded with a mig, although tig would be preferred if that's an option.
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SugarHillCTD
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PostPosted: Fri Jun 16, 2017 6:43 pm    Post subject: Reply with quote

If you electric weld while on the bike- unplug the engine and ABS brain first.

There have been folks that didn't and fried their (expensive) electronics.
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N41EF
Flying Brick Rider


Joined: 23 Mar 2014
Posts: 316
Location: Aiken, SC

PostPosted: Fri Jun 16, 2017 7:30 pm    Post subject: Reply with quote

My thoughts, even if you COULD weld it on the bike, I'd take it off because of clearance. Buy the 4 new copper exhaust gaskets, and the 8 new nuts for the tubes. I had a small leak on the flanges because the 24 year old nuts had vibrated loose. They don't get torqued very tight, so new coppers and nuts keep it together. As Duck mentioned its the 8 nuts, big bolt by left foot peg, and small nut under right side from back going toward the front. You can unplug the O2 sensors or just unscrew it.
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Flying Duck
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Joined: 27 Jan 2005
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Location: Bumf***, WA

PostPosted: Sat Jun 17, 2017 1:56 am    Post subject: Reply with quote

And if you're going to take it off, you'll find it MUCH easier to disconnect the lead for the O2 sensor than to get the O2 sensor unscrewed from the exhaust. (At least from my experience.) Those threads get exposed to lots of moisture down there combined with some pretty extreme thermal cycles.
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getlunch
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Joined: 14 Mar 2008
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Location: seattle

PostPosted: Sat Jun 17, 2017 4:03 am    Post subject: Reply with quote

I have welded the collector area on my muffler a few times. Even with gussets welded into place cracks still occurred. The hardest part is if the cracks happen in the middle inside portion of the collector. This requires a fair amount of cutting back to create access to weld the inside of the header tube and then reattaching what was removed to gain access.

The first time things were tack welded in place, with bike brains disconnected, another time I made a metal jig to hold everything in place and welded everything while unattached. Second and third go around an attempt to temper/anneal the HAZ(heat affected zone in welder lingo) seemed to be moderately successful.

In a conversation with a high end fabricator well versed in metallurgy, his conclusion is that BMW had various suppliers of tubing with some lots not being the ideal specs resulting in the never ending cracking of some mufflers while others go forever with no cracking.

If I can find the pics I will post them up.
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'92 K100RS
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Scott_Anderson
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Joined: 05 Sep 2006
Posts: 2880
Location: Central Iowa, USA

PostPosted: Sat Jun 17, 2017 7:49 am    Post subject: Reply with quote

I highly doubt the metallurgy theory, I believe more of a poor design issue.
Reason being it is only affecting the 16V version bikes where the tubes are welded directly to the collector. Can't withstand vibration when the head end mounting nuts get loose and/or the rear support rubber wears out and can't keep the rear aligned properly putting stress at the weld joint.
The earlier versions had sleeves welded to the collector then the tubes were inserted into the tubes without welding. Vibration tolerant.
I can't say as I've ever heard of a K75 or K100 8v owner having this issue.
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Flying Duck
PsyKotic Waterfowl


Joined: 27 Jan 2005
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Location: Bumf***, WA

PostPosted: Sat Jun 17, 2017 10:03 am    Post subject: Reply with quote

Not to mention that it's a pain in the butt that the headers don't separate from the can making it a heavy, unwieldy part to deal with.

The K100 system wasn't that much better though. Lining up and tightening the individual header pipes to the can is a real pain.

They got it right on the K75 though. The headers and collector are one piece that's pretty easy to hook up to the can.
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94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)
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Al.
Flying Brick Rider


Joined: 28 Oct 2005
Posts: 292
Location: West of Ireland

PostPosted: Sun Jun 18, 2017 5:15 pm    Post subject: Reply with quote

Thanks for all the comments
Any comments on ease of unbolting of headers?
Did any shear off??
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Flying Duck
PsyKotic Waterfowl


Joined: 27 Jan 2005
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PostPosted: Sun Jun 18, 2017 5:20 pm    Post subject: Reply with quote

12mm deep well socket.

I've removed tons of K exhausts and never had any of the header flange bolts shear.

Worst case the nut is stuck and it unscrews the bolt into the head. Not a big deal.

You might want too consider putting in fresh header gaskets when you reinstall.
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93 K11LT
94 K11RS- "Kato"
86-97 K75F (K75/100/1100 Frankenbrick)
86 K75C w/ paralever, high perf. cams,TURBO!
91 K1
86 custom K100
and 2 more
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE
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whyoldbill
Flying Brick Rider


Joined: 12 Jun 2006
Posts: 440
Location: in the boonies, northwest of Columbus, Ohio

PostPosted: Sun Jun 18, 2017 10:45 pm    Post subject: Reply with quote

Flying Duck wrote:


Worst case the nut is stuck and it unscrews the bolt into the head. Not a big deal.

You might want too consider putting in fresh header gaskets when you reinstall.


+1 on the frozen nuts. They're copper and somehow seize to the steel bolt.
Heat them to a pretty glowing red color (mapp gas torch does a nice job) and they'll come right off and leave the stud in the head.
BMW stealer had new nuts in stock, if that tells you anything
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The desired effect is what you get when you improve your interplanetary funksmanship - George Clinton
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N41EF
Flying Brick Rider


Joined: 23 Mar 2014
Posts: 316
Location: Aiken, SC

PostPosted: Mon Jun 19, 2017 9:33 pm    Post subject: Reply with quote

I just squirted mine with penetrant, and they came right off with everything cool. I did replace the 4 gaskets and all 8 nuts with the new copper ones. I needed a ratcheting wrench for one of them sockets got the rest.
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552255
Mad Brick Rider


Joined: 13 Aug 2010
Posts: 94
Location: Nebraska

PostPosted: Wed Jun 21, 2017 11:45 am    Post subject: Reply with quote

I have a whole, 'uncracked' exhaust in excellent condition, with new copper rings, o2 sensor for sale on on ebay...if your interested let me know.

I welded the exhaust on my bike...2-3 times? it kept cracking, and it was a going to be a temp. fix, so I bought this exhaust. I never used it, and just recently sold the K1100...so have some parts for sale.

About welding, do it on the bike unless you have a jig to to 'hold' header pipes etc. I had to heat and bend a pipe in order to even get it to fit back on bike, and it wasn't easy.
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